In a fixed infrastructure network, mobile devices and sensors must connect to an access point like a base station to use the network. However, in a mobile ad-hoc network (MANET), the network organization is self-organizing and can change as devices and sensors move. Nodes in a MANET function as both hosts and routers, allowing the network to be established across multiple intermediate nodes. The connectivity and available routes in a MANET depend on the locations of nodes and their ability to discover services and route messages through nearby nodes.

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Mobile Ad-hoc and Sensor Networks
Lesson 01
Introduction to Mobile Ad-hoc
Network (MANET)

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Fixed infrastructure network
• Networking using switches, hubs,
routers, access-points, base stations, or
gateways networked
• Switches, hubs, or routers locations fixed
• To connect to and access the network a
mobile device or wireless sensor has to
be moved in the vicinity (connectivity
range) of an access-point
• Example─ a cellular network

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Fixed Network Infrastructure
architecture

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Fixed Infrastructure
• Each mobile device or sensor
connects to an access-point, base
station, or gateway with a switch,
hub, or router A

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A Switch in fixed infrstructure
• Provides connectivity between the
two, a hub functions as a central
switching exchange

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A router in fixed infrastructure
• Provide two or more paths to route a
message or packet so that the available
path can be used at an instant
• They function as the nodes of the
network
• A mobile device or sensor has to acquire
an access-point or node of the fixed
infrastructure network before being able
to connect to another

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GSM Cellular phones in a fixed
infrastructure network
• GSM system─ A three-subsystems
architecture consisting of radio subsystem
(RSS), network subsystem (NSS), and
operational subsystem (OSS)
• Each cellular phone has to first connect to
a RSS of GSM public land mobile network

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Cellular phones in a fixed
infrastructure network
• The connectivity between two cellular
phones is ensured through GSM public
land mobile PSTN, ISDN, or PSPDN
networks

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Problem with fixed infrastructure
network
• Disconnection from the network and thus
unable to communicate through the
network when a wireless sensor or mobile
device moves out of the range of access-
point, base station, or gateway having the
switch or router
• Even though there may be another
wireless device in its vicinity connected to
network

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Problem with fixed infrastructure
network
• Network not usable in operations like
disaster relief

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Mobile ad-hoc network (MANET)
• A network in which the locations of the
switches, hubs, or routers can be mobile
• The number of routers available at an
instant can increase or decrease, and
the available routing paths can change
• The mobile devices or wireless sensors
as well as the access-points can have
switches or routers

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Mobile ad-hoc network (MANET)
architecture

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MANET Organization
• The ad-hoc network formed by the nodes
A, C, D, E, F, and G
• Each mobile device or sensor functions
as a node with a switch or router

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The network organization
• Change if D and E move away from each
other such that they reach out of the
range of wireless coverage
• Two new ad-hoc networks will then be
formed by (i) A, C, and D and (ii) A, G, F,
and E
• The devices on two networks can still
connect to each other through the
common node A

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MANET Organization
• An important characteristic of ad-hoc
network architecture is that its
organization can change due to
movement of a device or sensor
• In other words, the ad-hoc networks are
self-organizing

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MANET
• The routes available to the mobile
devices or wireless sensors can thus
change at any time
• Depend on presence and locations of
other wireless devices in their vicinity
(connectivity range)

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MANET organization
• Depends upon the location of the nodes,
their connectivity, their service discovery
capability, and their ability to search and
route messages using nearest node or
nearby nodes

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Example of network of mobile device,
home computer and printer at office
• A Bluetooth-enabled mobile device, a
Bluetooth-enabled computer, and
Internet with WiFi connection at home
• Assume that there is a Bluetooth-
enabled computer connected to TCP/IP
Internet and also to JINI client printer at
office

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Example of network of mobile device,
home computer and printer at office
• Through intermediate nodes WiFi,
Internet, and office computer, an ad-hoc
network establishment between the
mobile device at home and printer at
office when the user carrying the device
moves from office to home and handheld
PDA mobile device reaches near the
home computer

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Network of mobile device, computer and
printer Using service discovery
• A MANET establishes after the services
of JINI, TCP/IP Bluetooth, and WiFi
discovered
• When the user of same mobile device
goes to an airport with WiFi connectivity,
a MANET again established with the
office printer

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Summary
• To connect to and access the network a
mobile device or wireless sensor has to
be moved in the vicinity (connectivity
range) of an access-point in fixed
infrastructure network
…

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… Summary
• Connection depends upon the location of
the nodes, their connectivity, their
service discovery capability, and their
ability to search and route messages
using nearest node or nearby nodes in
Mobile Ad-hoc network (MANET)

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End of Lesson 01
Introduction to Mobile Ad-hoc Network